Elevation Band Material Sandcastle broken with WebGL2 context

[ebogo1]

With a WebGL2 context, the elevation band material doesn't show up. Console prints a bunch of WebGL warnings:

[.WebGL-0x7fe337081c00]GL ERROR :GL_INVALID_OPERATION : glTexImage2D: invalid internalformat/format/type combination GL_LUMINANCE/GL_LUMINANCE/GL_FLOAT
[.WebGL-0x7fe337081c00]RENDER WARNING: texture bound to texture unit 3 is not renderable. It might be non-power-of-2 or have incompatible texture filtering (maybe)?

Sandcastle example: link

Browser: Chrome 97

Operating System: macOS 11.6